Hello, the answer depends on the surgeon's training and experience and the type of hernia. Most of the time, the surgeon will be able to detect a hernia prior to surgery and if they don't feel that they can repair it, they will consult with a general surgeon to do this part of the operation.
YES, a plastic surgeon can fix a hernia. Most of us did a general surgery residency before entering our plastic surgery fellowship training, so we are very well qualified to fix a hernia.